Mesoporous materials have pores with diameters between 2 nm and 50 nm, the presence of which generally decreases the thermal conductivity of the material. By incorporating mesoporous structures into thermoelectric materials, the thermoelectric properties of these materials can be improved. Although TiO 2 is an ordinary insulator, reduced TiO 2 shows better electrical conductivity and is therefore a potential thermoelectric material. Furthermore, the addition of a dopant to TiO 2 can improve its electrical conductivity. We hypothesized that, by doping ordered mesoporous TiO 2 films with niobium, we would be able to minimize the thermal conductivity and maximize the electrical conductivity. To investigate the effects of Nb doping and a mesoporous structure on the thermoelectric characteristics of TiO 2 films, Nb-doped mesoporous films were investigated using x-ray diffraction, ellipsometry, fourpoint probe measurements, and thermal conductivity analysis. We found that Nb doping of ordered mesoporous TiO 2 films improved their thermoelectric properties.
Ordered mesoporous TiO2 films with incorporated Pt nanoparticles were prepared using titanium tetraisopropoxide, hexachloroplatinic acid hexahydrate, and Pluronic P-123 as a titania precursor, a Pt precursor, and a structure-directing agent, respectively. Pt nanoparticles were introduced to enhance the electrical properties of the mesoporous films, which have excellent thermal insulation properties. We confirmed that the synthesized composite films with Pt nanoparticles had an ordered pore structure with anatase phase TiO2 by both small-angle and wide-angle X-ray diffraction analyses. Although the porosity of the composite film decreased from 37.6 to 29.3% when Pt nanoparticles were included, the conductivity ratio (σ/κ) of the film increased greatly, up to approximately 1370 K V-2, due to the greater increase in electrical conductivity than thermal conductivity. Based on our results, we conclude that by incorporating Pt nanoparticles into ordered mesoporous TiO2 film, the thermoelectric properties of the mesoporous films can be improved.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.